Android EditText 字数限制

mChatMsgEt.addTextChangedListener(new TextWatcher() {
    private int limit = 200; // 字数限制
    private CharSequence beforeSeq; // 保存修改前的值

    private int afterStart;
    private int afterCount;

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        if (s.length() + (after-count) > limit) {
            beforeSeq = s.subSequence(start, start + count);
            toastMsg("不能超过" + limit + "字！");
        }
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        if (count > before && s.length() > limit) { //如果字符数增加时，且当前字符数超过限制了, 保存原串用于还原
            afterStart = start;
            afterCount = count;
        }
        mMsgLimitTv.setText(String.format("%s/" + limit, s.length()));
    }

    @Override
    public void afterTextChanged(Editable s) {
        if (s.length() > limit) {
            try {
                s.replace(afterStart, afterStart + afterCount, beforeSeq);
            } catch (IndexOutOfBoundsException e) {
                Log.d(TAG, Log.getStackTraceString(e));
            }
        }
    }
});